Joint.



G. A. KRAUS.

JOINT. APPLICATION FILED MAR. 2, 1910. RENEWED APR. 5, 1912.

1,046,085. Patented Dec. 3, 1912.

Fig.2-

WIT EIEI-; VEHTER: $44.4), MW

COLUMBIA PLANOGRAPH C0, WASHINGTON, D. c.

CHARLES A. KR AUSpOF NEWTON HIGHLANDS, MASSACHUSETTS.

JOINT.

Specification of Letters Patent.

Patented Dec. 3,1912.

Application filed March 2, 1910, Serial No. 546,959. Renewed April 5, 1912. Serial No. 688,789.

To all whom it may concern:

Be it known that I, Crmnnns A. KnAUs, a citizen of the United States, and resident of Newton Highlands, in the county of Middlesex and State of Massachusetts, have in vented new and useful Improvements in Joints, of which the following is a specification.

My invention consists in improvements in gas tight joints such as are shown, described and claimed in an application for United States patent, Serial No. 514,859, filed by me .etugnst 2?, 1909, and the materials which I prefer to employ in the construction of my improved joint are therein fully set forth and described. As I have pointed out in the specifications of the said application, a necessary condition for the production of a gas tight joint between metal members,

i made by an adhesive vitreous intermediary,

is that under all conditions of use the successive members which form the joint shall be under compression by an outer member. My improvements herein described are addressed to this essential condition, and are designed to obviate the maintenance of diverse temperature conditions during the cooling of the joint, so that a uniform subsiding annealing heat may be employed in the last stage of manufacture.

The joint comprises two tubular metal Jembers, so proportioned as to form a lapjoint, one within the other. Preferably the outer member is conically flared and the inner member conically tapered. An intermediate sleere of vitreous or similar refractory material is intimately fused to both the lapping metal members, preferably, as set forth in my said application for patent, by the aid of a low-melting flux which has the:

property of dissolving the oxid of the metal of which the members are made. The inter mediate sleeve has, moreover a lower coefficientof expansion than the metal members. In order to maintain close union between the inner metal member and the intermediary, I attach, as by an oxid-dissolving flux, a fairly thick lining of vitreous refractory material to the inside of the inner metal member. The lap portion of this inner metal member should be thin enough to stretch during the process of cooling the joint, so that, in spite of the superior coeflicient of expansion of the metal, it will remain in intimate contact with the sleeve of insulating material lying between the metal members. For soft steel and copper tubes, I find that a thickness from 1/32 to 1/16 inch gives satisfactory results.

While I recommend the use of a strut sleeve composed of insulating material, in some cases it may be advantageous to employ a metal strut instead. Alloys of iron and nickel may be thus employed, the composition of the alloy being so chosen as to possess the proper coeflicientof expansion.

Referring to the drawings,-in Figure 1 there is illustrated a simple form of insulating gas-tight joint which expresses my invention. The metal tubes A and B are provided with mutually fitting conical ends A and B, the tapered end B being preferably reduced in thickness, and also, preferably, composed of ductile metal, such as copper. An insulating sleeve or lining of glass G is fused between and to the two ends A and B, and an inner sleeve C which I term a strutsleeve, of similar material, is fused as a lining to the inner tubular end B. The intimate union of these linings with the metal is best secured by employing a low-melting flux, like borax, which dissolves the metallic oxids and insures perfect union between the metals and the vitreous materials. The inner sleeve C is of material which has a lower coefficient of expansion than the metal of which the tubular end B is composed. When the joint, thus formed, has been thoroughly and uniformly heated so that all the members are in intimate union, it is placed in an annealing furnace and gradually cooled. The strut C and the lining C become rigid at essentially the same temperature and as the temperature falls the metal members begin to exert a stress of compression upon them. The metal members themselves are therefore subjected to tension. Vitreous materials, such as are employed in the joints here described, possess enormously greater resistance to compression than the inclosing metal members possess with respect to tension. Accordingly the metal members are stretched as the joint cools, their position and form being determined by the vitreous members. The inner metal member B is thus made to remain in intimate contact with the insulating lining case demand it, steel or other metal of high elastic limit may likewise be successfully employed. I recommend a steel tube for the external metal member, and a thin copper tube for the inner metal member.

, The structure shown in Fig. 2 is substantially the same as that of Fig. 1; an enlargement, A on the outer tubular member is provided, and a glass insulating sleeve D is slipped into the space between A and B.

By employing a strut-sleeve as C, and an inner metal member thin enough and ductile enough to stretch in cooling, oints may successfully be made between tubular metal members of considerable size. As such joints may be cooled slowly in an annealing oven, they are insured against the strains due to abrupt temperature variations, and the whole structure is rendered more permanently stable than when a part has to be cooled more rapidly than other parts.

hat I claim and desire to secure by Letters Patent is:

l. The combination of lapped tubular met-a1 members, an intermediate insulating sleeve joined to the metal members, and a strut-sleeve lining the inner met-a1 member, composed of material of which the coefficient of expansion is less than that of the inner metal member.

2. The combination of lapped tubular metal members, an intermediate insulating sleeve joined to the metal members, and a strut-sleeve lining the inner metal member, composed of material of which the coefficient of expansion is less than that of the inner meta]. member, said inner metal member being reduced in thickness at the joint.

3. The combination of lapped tubular metal members, an intermediate insulating sleeve comprising a low melting vitreous flux solvent of the oxid of the metal compos ing one or both of the metal members, and a strut-sleeve lining joined to the inner metal member, composed of material of which the coefficient of expansion is less than that of the inner metal member.

4. The combination of lapped tubular metal members, an intermediate insulating sleeve comprising a low melting vitreous flux solvent of the oxid of the metal composing one or both of the metal members, and a strut-sleeve lining joined to the inner metal member, composed of material of which the coefficient of expansion is less than that of the inner metal member, said inner metal member being reduced in thickness at the joint.

5. The combination of lapped tubular metal members, the inner member being composed of copper, an intermediate insulating sleeve joining the metal members, and a strut-sleeve lining the copper member, composed of material of which the coefficient of thermal expansion is less than that of copper.

6. The combination of lapped tubular metal members, the outer member being composed of steel and the inner being composed of copper, an intermediate insulating sleeve joining the metal members, and a strut-sleeve lining the inner member, composed of material whose coefficient of thermal expansion is less than that of copper.

7. The combination of lapped tubular members, an intermediate insulating sleeve joining the metal members composed of material whose coefficient of thermal expansion is less than that of the metal members and a strut-sleeve lining the inner metal member, composed of material whose coeflicient of thermal expansion is the same as that of the insulating sleeve.

Signed by me at Boston, Massachusetts, this twenty-fourth day of February, 1910.

CHARLES A. KRAUS.

\Vitnesses:

ROY D. MAILEY, CHARLES D. Woonnnnny.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents. Washington, D. C. 

